JPH1143055A - Steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device capable of stably relaxing impact load taking place at a steering shaft though the device is compact in constitution. SOLUTION: In this steering device 100, a disc spring 105 is interposed between a first rack support 104 and a second rack support 106, when it is subjected to force in the direction that a pinion 11a is parted from a rack shaft 112 at the time of usual steering, the first and second rack supports 104 and 106 act as a solid body each, however as they are so designed as to be relatively moved when they are subjected to impact load, they can stably absorb impact load only when impact load takes place without hindering a rack support function. Furthermore, since the disc spring 105 as mentioned above can be incorporated in the inside of the rack support, the steering device can thereby be made more compact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device, and more particularly to a rack support mechanism for a rack and pinion type steering device.

[0002]

2. Description of the Related Art As a steering device for a vehicle, a rotational output of an electric motor or the like is reduced by a gear device and transmitted to a rack shaft of a steering mechanism, and a manual force applied to a steering wheel is assisted to rotate the rack shaft. There is known a so-called rack and pinion type power steering device configured to steer wheels by reciprocating within a predetermined range.

[0003]

By the way, the steering wheel attached to the upper end of the steering shaft has a size of 40 cm.
Due to the front and rear diameters, the moment of inertia is relatively large. Moreover, in recent years, an airbag, which is a shock absorbing device, is often mounted on a steering wheel. In such a case, the moment of inertia of the steering wheel is further increased.

On the other hand, although the moment of inertia of the steering shaft itself is small, in the above-described power steering apparatus, the steering shaft is connected to the electric motor via the gear mechanism, so that the moment of inertia of the steering wheel and the moment of inertia of the steering wheel are reduced.
The moment of inertia of the electric motor (moment of inertia of rotor × square of reduction gear ratio) is added to the steering shaft.

[0005] Here, for example, when the steering wheel is vigorously rotated, the moment the rack shaft hits the rack stopper, if only the steering shaft, the vehicle immediately stops. However, since the steering shaft is connected to a steering wheel having a large moment of inertia or a rotor of an electric motor, the steering shaft tends to continue to rotate. At this time, a large impact load acts on the steering shaft.
Such impact loads generate loud striking sounds and vibrations, and cause discomfort to the occupants.

As a method for solving such a problem, a torque limiter using a frictional force is provided on a rotating shaft of an electric motor, and the torque limiter is actuated at the moment when an impact load is applied, so that the steering shaft is electrically connected to the electric motor. Disconnect from the motor,
It has been proposed to reduce the impact load thereby.

However, in the case of a torque limiter using a frictional force, there is another problem that the operation start condition of the torque limiter fluctuates due to an impact speed, temperature, and the like, and stable impact load cannot be relaxed.

On the other hand, another method has been proposed in which an impact load is reduced by abutting a rack shaft on an elastic body at a stroke end thereof. However, according to such a method, the elastic body that makes the two ends of the rack shaft contact each other is two
The cost must be increased, the manufacturing cost increases, and a certain adjustment is required to equalize the shock absorption characteristics of both elastic bodies. In addition, in order to stably absorb the shock, it is necessary to secure a space for the rack shaft to move in response to the deformation of the elastic body when absorbing the shock, and the stroke of the rack shaft is reduced accordingly. There's a problem.

Accordingly, the present invention has been made in view of such a problem.
It is an object of the present invention to provide a steering device capable of stably reducing an impact load generated on a steering shaft while having a compact configuration.

[0010]

In order to achieve the above object,
A steering device according to the present invention includes a housing, a steering shaft rotatably supported by the housing and having a pinion formed on an outer periphery thereof, and a rack tooth meshing with the pinion, and according to rotation of the steering shaft. A rack shaft that steers wheels by reciprocating with respect to the housing, a support portion that supports the rack shaft, and a biasing member that biases the rack shaft toward the pinion via the support portion A rack support device having the following, and provided between the urging member and the support portion of the rack support device, when a force is applied in a direction in which the pinion and the rack shaft are separated during normal steering. Comprises a shock absorbing device that maintains a constant distance between the urging member and the support member, but shortens the distance when receiving an impact load exceeding the force.

[0011]

According to the steering device of the present invention, the shock absorbing device is provided between the biasing member of the rack support device and the support portion, and the pinion and the rack shaft are normally connected to each other during normal steering. When receiving a force in the direction of separating, the distance between the biasing member and the support member is maintained constant, but when a shock load exceeding the force is received, the distance is shortened. Therefore, it is possible to stably absorb the impact load only when an impact load is generated without obstructing the function of the rack support device. In addition, such a shock absorbing device can be incorporated in the rack support device, thereby making it possible to reduce the size of the steering device.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an electric power steering apparatus according to a first embodiment of the present invention mounted on a vehicle. FIG.
FIG. 1 is an axial partial cross-sectional view of a steering device 100 according to the present embodiment.

In FIG. 1, an electric power steering device 50 fixed to a vehicle includes a steering shaft 5.
A steering wheel 52 is attached to the upper end of the steering wheel 52. On the other hand, the lower end of the steering shaft 51 is connected to an intermediate shaft 54 via a universal joint 53, and the intermediate shaft 54 is connected to an input shaft 111 of the steering device 100 via a universal joint 55.

The controller 50b of the electric power steering device 50 includes a torque detector 50b and a battery 5
0c and a speed detector 50d, and drives and controls the electric motor 50e in a manner described later to output an appropriate auxiliary steering torque.

In FIG. 2, the steering device 100
Has a housing body 101 and a rack column 110 extending therefrom. The housing main body 101 and the rack column 110 are fixed to a vehicle body (not shown) by brackets 110a and 110b, and the housing is formed integrally therewith.

Inside the housing body 101, an input shaft 111 having one end connected to the intermediate shaft 54 via a universal joint 55 extends obliquely from above, while the housing body 101 and the rack column 110 The rack shaft 112 extends inside.

Ball joints 115 (only one is shown) are attached to both ends of the rack shaft 112, and tie rods 117,
The end of 118 is pivotally mounted. Dust-proof boots 1 around the ball joints 115 and 116
19 and 120 are attached.

FIG. 3 is a view of the steering device 100 of FIG. 2 cut along line II-II and viewed in the direction of the arrow. FIG.
2, the housing main body 101 has a shape in which a small cylinder 101b is joined to a large cylinder 101a at right angles. A pinion 111a is formed at the lower end of the input shaft 111 inserted into the large cylinder 101a, and meshes with the rack teeth of the rack shaft 112. The rotation of the input shaft 111 causes the rack shaft 112 to move in the longitudinal direction ( (Perpendicular to the paper).

The input shaft 111 is mounted on the housing 101 by bearings 102a and 102b on both sides of the pinion 111a.
Are rotatably supported. Lock nut 10
3a allows the bearings 102a, 102b to be preloaded via the input shaft 111. Note that a seal 10 is provided between the lock nut 103 and the bearing 102a.
3a is arranged.

Small cylinder 101b of housing body 101
Extend outward from the rear surface of the rack shaft 112.
On the back of the rack shaft 112, a cylindrical support surface 104a is provided.
The first rack support 104 is disposed such that the first rack support 104 abuts on the rack shaft 112. The rack shaft 112
The first rack support 104, which is a support portion of the first embodiment, has a concave portion 104b formed inside, and the concave portion 104b has
A pair of disc springs 105 are installed facing each other. Further, after the disc spring 105 is pressed against the first rack support 104 by the second rack support 106 to apply a predetermined initial load, the first rack support 104 and the second rack support 105 are fixed by the retaining ring 107. doing.
In addition, the first rack support 104, the disc spring 105,
The second rack support 106 and the retaining ring 107 constitute an impact absorbing device.

On the other hand, a cover member 109 is screwed to the end of the small cylinder 101b. A coil spring 108, which is an urging member, is provided between the cover member 109 and the second rack support 106, and applies an urging force to the rack shaft 112 via the second rack support 106 and the first rack support 104. To prevent the pinion 111a from hitting the rack shaft 112. Note that the cover member 109 and the second rack support 1 are adjusted so that the biasing force can be adjusted by tightening or loosening the cover member 109.
A slight gap is formed between the gap and the gap No. 06.

Next, the operation of the electric power steering apparatus according to the present embodiment will be described below with reference to FIG. When the driver rotates the steering wheel 52, the steering shaft 51, the universal joint 53, the intermediate shaft 54, the universal joint 55, and the input shaft 111 rotate to move the rack shaft 112 in a predetermined direction. In this case, the value of the torque detected by the torque detecting device 50b is sent to the controller 50a, where it is compared with a predetermined value determined in consideration of the output of the speed detector 50d and the like.

When the torque exceeds a predetermined value,
Since the auxiliary steering force is required, the electric motor 5
0e to drive the electric power of the battery 50c with the electric motor 5
0e. The driven electric motor 50e outputs an auxiliary torque to the steering shaft 51 to move the rack shaft 112 in the axial direction. Torque detection device 50b
When the value of the torque detected at is lower than the predetermined value, the auxiliary steering force is unnecessary, and the electric motor 50e is not driven.

In FIG. 3, the force in the separation direction generated between the pinion 111a and the rack shaft 112 during normal steering can be suppressed by the urging force of the coil spring 108, whereby the pinion 111a and the rack shaft Tapping with 112 can be prevented.

In such a case, the disc spring 1 disposed between the first rack support 104 and the second rack support 106
In the first rack support 1, an initial load larger than the force in the separation direction generated between the pinion 111 a and the rack shaft 112 during normal steering is set.
Since the first rack support 104 and the second rack support 106 act as a rigid body, the urging force of the coil spring 108 is transmitted to the rack shaft 112 because the 04 and the second rack support 106 are connected by the retaining ring 107. be able to.

On the other hand, when the driver vigorously rotates the steering wheel 52, the rack shaft 1
As soon as 12 hits the end 110c (FIG. 2) of the rack column 110, the steering wheel 52 having a large moment of inertia and the steering shaft 51 connected to the rotor of the electric motor 50e continue to rotate.

Therefore, even though the rack shaft 112 is stopped, the input shaft 111 attempts to rotate with a large torque, so that a large impact load is generated between the input shaft 111 and the rack shaft 112. Here, since the initial load of the disc spring 105 is set to be smaller than the applied impact load, when the impact load occurs, first, the coil spring 108 is contracted, and the second rack support 106 is attached to the cover member 109 at the end. Thus, the disc spring 105 is crushed or elastically deformed for the first time, and the impact load can be absorbed by this action.

FIG. 4 is a sectional view similar to FIG. 3 of a steering device 200 according to a second embodiment of the present invention. Note that the second embodiment will be described focusing on differences from the first embodiment shown in FIG. 3, and detailed description of common parts will be omitted.

The second embodiment shown in FIG. 4 differs from the first embodiment in the configuration of the rack support.
More specifically, a first abutment on the back of the rack shaft 112 is provided.
The coil spring 20 is provided between the rack support 204 and the second rack support 206 opposed thereto.
8 are provided. On the other hand, the second rack support 206
A disc spring 205 is disposed between the cover member 209 in which the
The rack support 206 and the cover member 209 are connected to the retaining ring 2.
07.

As in the first embodiment, the disc spring 205 disposed between the second rack support 206 and the cover member 209 has a pinion 111 generated during normal steering.
Since the initial load larger than the force in the separation direction generated between the first rack support 206 and the rack shaft 112 is set, the second rack support 206 and the cover member 209 act as a rigid body,
The rack shaft 112 can be pressed toward the pinion 111a based on the urging force of the coil spring 208.

On the other hand, when an impact load occurs, the initial load of the disc spring 205 is set to be smaller than the applied impact load, so that the coil spring 208 first contracts, and the first rack support 204 is attached to the cover member 209 by the end. At the attached stage, the disc spring 205 is crushed or elastically deformed for the first time, and the impact load can be absorbed by this action.

Although the present invention has been described with reference to the embodiments, the present invention should not be construed as being limited to the above embodiments, and it is needless to say that modifications and improvements can be made as appropriate. is there. For example, the disc spring or coil spring may be another type of spring.

[0033]

As described above, according to the steering device of the present invention, the shock absorbing device is provided between the urging member of the rack support device and the supporting portion, and the shock absorbing device is connected to the pinion during normal steering. The gap between the biasing member and the support member is kept constant when receiving a force in a direction in which the rack shaft is separated from the rack shaft, but the gap is shortened when an impact load exceeding the force is received. Therefore, the impact load can be stably absorbed only when an impact load is generated without obstructing the function of the rack support device. In addition, such a shock absorbing device can be incorporated in the rack support device, thereby making it possible to reduce the size of the steering device.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which an electric power steering apparatus according to a first embodiment of the present invention is mounted on a vehicle.

FIG. 2 is a steering device 100 according to the embodiment;
3 is a partial cross-sectional view in the axial direction of FIG.

FIG. 3 is a view of the steering device 100 of FIG. 2 cut along a line II-II and viewed in an arrow direction.

FIG. 4 is a sectional view similar to FIG. 3 of a steering device 200 according to a second embodiment of the present invention;

[Explanation of symbols]

 101 Housing main body 101b Small cylinder 102a, 102b Bearing 103 Lock nut 104, 204 First rack support 105, 205 Disc spring 106, 206 2 Rack support 107, 207 Stop ring 108, 208 Coil spring 109, 209 Cover member 111 Input shaft 112 Rack shaft

Claims (1)

[Claims] A steering shaft rotatably supported by the housing and having a pinion formed on the outer periphery thereof; and a rack tooth meshing with the pinion, wherein the rack teeth are rotated in accordance with the rotation of the steering shaft. A rack shaft that steers wheels by reciprocating with respect to the housing, a support portion that supports the rack shaft, and a biasing member that biases the rack shaft toward the pinion via the support portion. A rack support device having, when provided between the urging member and the support portion of the rack support device and receives a force in a direction in which the pinion and the rack shaft are separated during normal steering, A steering device comprising: a shock absorbing device that maintains a constant distance between the urging member and the support member, but shortens the distance when receiving an impact load exceeding the force. .